Inside corner profile for drywall installation

ABSTRACT

An inside corner profile for providing a low-maintenance expansion joint in a space that is at least partially designed with flat structural elements, the cross section of the inside corner profile having a long leg on the back and a short leg on the front, as well as a web that connects the short leg and the long leg, the web being extended beyond the attachment point of the short leg and the web extension having a shadow gap on the back side of its end portion is disclosed.Also disclosed is a use of the inside corner profile in drywall construction using gypsum plaster board panels.

The present invention is to be assigned to the technical field of drywall installation.

The invention relates to an inside corner profile for providing a low-maintenance expansion joint in a space at least partially designed with flat structural elements, the cross section of the inside corner profile having a long leg on the back and a short leg on the front as well as a web that connects the short leg and the long leg.

The so-called frame construction is used in drywall installation. Flat structural elements are fastened to an internal framework made of horizontally and vertically extending profiles. The vertical profiles of the framing are also known as studs. Flat structural elements within the meaning of the invention include all construction panels (for example OSB panels, cement containing panels, gypsum plaster board panels, etc.) that can be used in drywall construction. A preferred area of application for the inside corner profile is gypsum plaster board panels, onto the edge portion of which the inside corner profile can be snapped (snap-on inside corner profile).

A gypsum plaster board panel of a drywall construction wall arranged on the inside of the room abuts with its end portion either on another gypsum plaster board wall or on an existing building wall, the two aforementioned walls usually being arranged at right angles with respect to the aforementioned gypsum plaster board panel. The resulting linear joint region forms one of the inside corners of the room.

It is known that expansion joints are formed in the inside corner regions and undesirably already indicate the seasonal thermal fluctuations by the formation of cracks. Static expansion movements in the building can likewise lead to cracking in the inside corner regions. Rendering the cracks in the inside corner region unrecognizable by an additional application of paint is often the reason for repainting an interior even though the inner walls in the region are not yet in need of maintenance.

The frequency of the interior painting required at regular intervals (room maintenance through repainting) could therefore be reduced if fewer cracks would appear in the inside corners and/or if they were less noticeable.

The joint design in the context of creating the interior spaces is therefore of great economic importance, because the type of joint design in the inside corners also determines the need of the interior spaces for maintenance.

Spackling the joints in the inside corner region with or without joint cover strips, without the use of other aids, is well known. Spackling requires tools with appropriate working edges to produce a corner region that is right-angled over the entire height of the room. The use of these tools requires fine, i.e. experienced, manipulation in order to achieve satisfactory work results. This is especially true when using joint tape, because it is easily damaged by the edges of the tools if the application experience is lacking.

For the shaping and visual aesthetics of inside corners, also taking into account the problem of expansion joints, various approaches to solutions using plastic or metal profiles are already known. These plastic or metal profiles are, on the one hand, profiles that, after they have been fixed, have to be fully integrated into the wall structure in a subsequent work step with the aid of a spackling compound (troweled in), and, on the other hand, they are snap-on profiles that do not require further work steps to be installed.

Plastic profiles are known which have either one fastening option (receptacle) or two fastening options for fixing the respective edge portion of the gypsum plaster board panels joined together in the inside corner region.

Inside corner profiles, each with, not just one, but two receptacles for the edge portion of flat structural elements, are known, for example, from DE 41 41 600 C1 and DE 81 28 252.4.

DE 41 41 600 C1 discloses a plastic profile for forming a connection transition between two planar structural elements adjoining each other at a right angle. The plastic profile has a receptacle for receiving the edges of the two structural elements. One of the receptacles has a U-shaped cross section. The other receptacle has a rectangular cross section. The elastic plastic bridge, which connects the two receptacles and thus forms the inside corner region, is made elastic due to the soft adjustment of the plastic. When using the profile known from DE 41 41 600 C1, a joint-like region is formed which in any case also has to be reworked in a known manner, for example by spackling or as a so-called acrylic joint by application of acrylic material.

DE 81 28 252.4 relates to a corner strip that also serves as an assembly aid. The corner strip according to DE 81 28 252.4 can be adapted as a guide strip to inside or outside corners that deviate noticeably from rectilinear and in any case has two fastening options/receptacles for the edge portions of the gypsum plaster board panels that form the inside corner. According to DE 81 28 252.4, the inside corner region itself is formed either by the plastic components of the profile or, alternatively, if the inside corner region is not filled by profile components, by a spackling compound to be worked into the inside corner region afterward. As a result, an inside corner region designed in accordance with DE 81 28 252.4 is as susceptible to crack formation due to stretching as an inside corner region designed without the corner strip.

In contrast to this aforementioned prior art, the present invention relates to a profile that has, not two receptacles, but only one receptacle, i.e. only one fastening option, for fixing the edge portion of a flat structural element arranged in the inside corner region.

In particular, the invention relates to the field of those inside corner profiles which have a portion that is U-shaped in cross section for receiving (fixing) the edge portion of a flat structural element, the U-shaped portion being particularly suitable for receiving (fixing) a gypsum plaster board panel (i.e. can be snapped onto the edge-side portion of a gypsum plaster board panel), and at least the front-side components of the profile forming the interior wall and being incorporated into the room decor finishing work, for example by application of a top coat of paint.

Profiles of the aforementioned category, i.e. inside corner profiles having only one receptacle (fastening option), for fixing the edge portion of a gypsum plaster board panel arranged in the inside corner region and for the visual and shape-giving design of the inside corner region, are also known from the prior art.

DE 20 2005 010 102 U1 discloses a construction panel connection profile which is intended to allow simple and quick laying of construction panels and which is intended to prevent thick joints between, on the one hand, the connection profile and, on the other hand, the construction panel to be installed. The connection profile from DE 20 2005 010 102 U1 has a portion with a U-shaped cross section for receiving the edge portion of a construction panel. One of the U-legs is designed at least in portions as a soft lip and its length is dimensioned such that it is shorter than the second back side leg. The soft lip, which, because of its flexibility, can prevent severe cracking in the region of the joint, is not tapered and rests on the outer side on the edge portion of the gypsum plaster board panel. This results in a visible step in the transition region, the height of which corresponds to the material thickness of the soft lip. This step-like offset must also be post-treated in an additional work step by spackling (=so-called troweling in).

Document GB 2 322 880 A discloses a bottom edge strip having an essentially U-shaped cross section for the edge-side reception of a bottom plate and a flexible, deformable cover strip which tapers to a point at the two end portions and which, due to its elasticity, rests both on the top of the bottom plate and against the wall and thereby fills the corner region of the floor-wall edge and gives it its visual appearance.

Document EP 2063 046 A1 discloses a ceiling edge strip which corresponds to the floor edge strip from GB 2 322 880 A in structure and function. The flexible cover strip tapering to a point at the end also protrudes into the U-shaped cross section in EP 2063 046 A1 and must be lifted when the gypsum plaster board panel is inserted.

The aforementioned cover strips made of flexible plastic have in common that, for the reasons explained above, in the region of the tip of the cover strip resting against the inner wall, noticeable cracks can still quickly form in the top coat of paint (emulsion paint) or in the finish coat of plaster (fine plaster, high-grade plaster).

As disclosed in EP 2063 046 A1 and GB 2 322 880 A, it is possible that the tip of a cover strip, which rests against the inside wall and has an aesthetically pleasing appearance, disadvantageously acts in the further course of time as a separation edge with respect to the top coat of paint during the new installation. This is because a line-shaped/strip-shaped region in which, experience has shown, the formation of cracks can be recognized particularly early runs exactly between the tip of a cover strip resting against the inner wall and the decorative layer (dispersion paint layer).

Furthermore, as with all elastic and/or flexible plastic materials, it is disadvantageous that the soft lip is made of a material which, due to its properties, necessarily contains a plasticizer and is precisely for this reason not characterized by high aging resistance.

In the case of the aforementioned known profiles, the soft lip protruding with one of its end portions into the U-shaped receptacle must also be widened at least in portions with an additional handle in order to introduce the edge portion of the construction panel.

Otherwise, there is a risk that the soft lip will be pressed into the U-shaped receptacle in an undesired manner by the edge of the construction panel to be introduced and that the introduction of the gypsum plaster board panel will fail completely in the initial approach. The assembly of a gypsum plaster board panel is made more difficult by the arrangement protruding into the U-shaped receptacle and the pretensioning of the soft lip.

At present, the post-treatment of the inside corners with an elastic joint material (e.g. acrylic, silicone, etc.) is probably one of the most frequently used methods for post-treating inside corners. Post-treating the inside corners with an elastic joint material is very time-efficient in the initial execution.

However, from the perspective of a person skilled in the art a joint filled with an elastic joint material is likewise always a “maintenance joint” due to the inevitable aging of the joint material.

The cracks in the elastic joint material often appear at a later point in time, because the joint material becomes brittle and therefore inelastic over time. In the aged state, the joint material can no longer compensate for expansion and tension and forms visible cracks, especially in the edge region.

At the same time, when an elastic joint material is used, it often happens that the interior decoration (emulsion paint) that is ultimately applied as a cover coat flakes off from the surface of the joint material early on.

It is possible that, precisely due to the aforementioned reasons, which concern the disadvantages of spackling or using elastic jointing materials, a large number of different profiles for solving the aforementioned problems are known in principle from the prior art.

Nevertheless, from the user's point of view, there is still a need for improvement over the known profiles with regard to ease of installation and the durability of the inside corner regions formed with the known profiles.

Against this background, the object of the invention is to provide an easy-to-install device with the aid of which the post-treatment of the inside corners in the region of the gypsum plaster board panels used is simplified after installation thereof and with the aid of which at the same time the need for maintenance of an inside corner region is reduced.

The object is achieved by an inside corner profile according to claim 1. Such an inside corner profile, the cross section of which has a long leg on the back and a short leg on the front, as well as a web that connects the short leg and the long leg to one another, is characterized in that the web is extended beyond the starting point of the short leg and the web extension has a shadow gap on the back of its end portion.

The shadow gap is formed by the web extension having a cross section that decreases from the starting point of the short leg toward the free end portion of the web extension. The reduction in cross section creates a free space on the back of the web extension with a constant distance between the existing wall and the back of the web extension. The spaced arrangement of two components results in a connection joint that is open toward the building interior. Such an open connection joint is also known as a “shadow joint.”

With the present inside corner profile, such a shadow gap can be designed very differently in many ways. Provision is made for the web extension to have either at least one bevel or at least one rabbet or a combination of the two on the back of its end portion.

The essence of the invention is that a shadow gap arranged on the back of the front end portion of the web extension or on the back of the end portion of the short leg of an inside corner profile, in particular a shadow gap formed as a bevel or as a rabbet, visually hides a color break of the paint applied on site with the effect of a visual screen.

In the case of the rabbet, the above-described effect of the shadow gap, compared to the bevel, which is implemented in one variant as a chamfer of the outer end portion of the web extension, is ensured in a particularly advantageous manner. This is because with a rabbet, the break line can be shifted far into the starting region of the shadow gap with a corresponding web extension. As a result the break line hidden from a viewer standing in the room by the web extension and is no longer obvious.

A bevel or a rabbet in each case forms a visually concealed joint region for the coat of paint adjacent to the inside corner profile. The color break that occurs at the bevel or at the rabbet is covered.

In particular, the shadow gap on the web extension (in contrast to the optional shadow gap on the inside end portion of the short leg) causes the color break line, as the length of the web extension increases, to be increasingly shifted into that profile region which is visually almost completely concealed from a viewer standing in the room and is therefore less or not at all detectable.

The outside of the bevel can be configured in different ways. The shape of the outer side of the bevel can be planar or curved inward, for example.

The execution of a shadow gap in the form of the combination: bevel-rabbet-bevel results in a shadow gap which reinforces the advantages of the invention, because an edge for the color break is provided in the region of each of the two bevels.

In principle, a corresponding continued design of the shadow gap as a combination of bevel-rabbet-bevel-rabbet-bevel is also conceivable.

With regard to the improved crack resistance in the case of inside corner designs, the profile also allows stresses to be reduced because it allows the panels to move in the profile or on the profile. The possible movement for the profile shown in FIG. 1 may be up to 0.5 mm. For the embodiments shown in FIG. 4 a, 4 b the tolerable movement is accordingly higher.

There are many different possibilities for the design of the front corner region formed by the front side of the short leg and the top side of the web extension.

Said corner region can be designed as a solid material or alternatively have one or more openings running in the longitudinal direction of the profile, which in the case of a plastic profile can be introduced by means of extrusion during manufacture. The alternative is advantageously associated with a lower cost of materials and at the same time lower weight. Stability of the inside corner profile is not impaired by the openings.

The design of the outside of the front corner region determines the overall appearance of the inside corner, which is visible due to the installation of the inside corner profile.

In a preferred embodiment, the aforementioned front corner region has a triangular cross section. This embodiment creates a visual texturing of the inside corner region by means of two joint lines running in parallel.

In an alternative preferred embodiment, the aforementioned front corner region has a cross section with a concave shape on the outside. An inside corner region formed by an inside corner profile of this embodiment has the appearance of an acrylic joint post-treated with the fingertip. This look is known as a fillet.

In a further alternative preferred embodiment, the aforementioned front corner region has a cross section with a convex outer side. The cross section of the corner region is similar in shape to a quarter circle and allows the inside corners to be decorated in the Baroque style.

In a particularly preferred embodiment, in addition to the web extension, the short leg also has a shadow gap on the back of its end portion, in particular a shadow gap in the form of a bevel or a rabbet, or a combination of at least one bevel and one rabbet.

This causes the creation of a second shadow gap on the same inside corner profile. The second shadow gap has the effect already explained above for the first shadow gap. The additional shadow gap on the inside end portion of the short leg is particularly useful if the edge of gypsum plaster board panel inserted into the U-shaped receptacle is to remain movable within the receptacle. This is the case, for example, when the inside corner profile is connected to the surface of the second wall forming the inside corner on the back of the web, for example by means of adhesive.

It is also conceivable that the surface of the shadow gap (i.e. the exposed inner side of the shadow gap) has a coating which reduces the adhesion of an emulsion paint to the surface of the inside corner profile in the region of the shadow gap. The reduction in the adhesion of the emulsion paint to the inside corner profile in the region of the shadow gap has two effect. First, it makes it easier to remove paint residues with the aid of a pointed tool before repainting in the region of the shadow gap. Second, the reduced adhesion between emulsion paint and the surface of the profile reduces occurrence of color breaks.

In a particularly preferred embodiment, the web has on the back, in the portion between the long leg and the short leg, a recess running along the longitudinal axis of the profile.

The recess can be shaped like a groove and have a square or semicircular cross section. The recess is used to hold an adhesive. It is preferred to accommodate a double-sided adhesive strip in a groove with a square cross section. The use of a double-sided adhesive tape with a foam intermediate layer is very particularly preferred.

Alternatively, the recess can also be shaped as a notch that is not as wide. The notch facilitates the spreading apart (widening) of the two legs when the inside corner profile is to be arranged on the edge of the flat structural element.

In a further very particularly preferred embodiment, the web has a combination of groove-like recess and notch in the bed of the along the longitudinal axis of the profile. The in combination with the recess running in the longitudinal direction, the profile in the groove bed also has a notch running in the longitudinal direction of the profile. The notch causes a desired kink point, which facilitates the spreading apart (widening) of the two legs when the inside corner profile is arranged on the edge of the flat structural element.

It goes without saying that the profile can be provided in a plurality of sizes (in particular with regard to the clearance dimension between the two profile legs for the adaptation to different gypsum plaster board panel thicknesses) in order to allow use with all common gypsum plaster board panel thicknesses.

To make it easier to fix the inside corner profile during assembly of the flat structural element, it is provided that a clamping effect acting on the outsides of the structural element starts from the two legs. The clamping effect is generated by the length of the web being dimensioned in such a way that the web length corresponds to the thickness of the flat structural elements used or is slightly less than the thickness of the flat structural elements used.

After the inside corner profile has been snapped onto the edge region of a flat structural element, the legs rest against this region with a slight clamping tension.

A particularly preferred area of application for the inside corner profile is gypsum plaster board panels, onto the edge portion of which the inside corner profile can be snapped.

In a further preferred embodiment of the inside corner profile, this has a plurality of needle-like, pointed elevations on the inner side of the long leg facing the gypsum plaster board for better adhesion to the edge portion of a gypsum plaster board panel.

The elevations can be pressed into the cardboard part of the gypsum plaster board panel with light pressure, so that the inside corner profile, possibly in addition to the clamping effect explained above, is additionally fixed even better to the gypsum plaster board panel.

This improved fixation can be an advantage if the gypsum plaster board panel still has to be moved or adjusted after the inside corner profile has been applied at the installation site.

The fixation can be mechanically strengthened in that the inside corner profile can be fixed to the gypsum plaster board panel using fastening means, such as screws. In this case, a plurality of circular openings for the implementation of a fastening means are arranged on the long leg.

The inside corner profile is preferably made of a plastic, particularly preferably a non-elastic plastic, such as a thermosetting plastic, or of aluminum. In principle, however, all other materials known to a person skilled in the art from the field of inside corner strips can also be used.

The advantages of the profile relate to its use in the assembly of gypsum plaster board panels that come up against another gypsum plaster board panel or an existing wall in the corner region. This assembly is quicker and easier when the profile is used. In addition, the corner regions in which the profile is arranged are less likely to need maintenance with regard to possible crack formation, or the interior spaces formed with the present inside corner profile allow repeated repainting without the need to consider previous color breaks, because the respective paint break edge of the new paint application in each case occurs below the shadow gap which acts as a screen. Thus previous color breaks cannot be perceived by the viewer as disturbing.

The inside corner profile is particularly easy to install because it can be arranged on the edge portion of a gypsum plaster board panel with just one handle and is then sufficiently firmly fixed for the further installation of the gypsum plaster board panel thereon by virtue of the aforementioned clamping effect.

After the profile has been fixed to the gypsum plaster board panel, the protective strip is removed from the prefixed double-sided adhesive tape with a foam layer in between. Then the gypsum plaster board panel to be installed is pressed into the corner. Finally, as is typical in drywall construction, the panel is attached to the substructure using mechanical fasteners (e.g. screws).

The use of this inside corner profile creates a clean, straight inside corner design that simplifies post-treatment. It is no longer necessary to trowel in or spackle (with or without separating strips) the panels that abut in the corner region when the inside corner profile is used.

The use of acrylic to create an expansion joint is also not required. Accordingly, the subsequent processing of the acrylic that has not yet hardened or the removal of acrylic residues is not necessary.

The inside corner profile accordingly allows a procedural approach to the construction of a drywall construction wall consisting of the following steps:

-   -   arrangement of the inside corner profile on the edge portion of         a gypsum plaster board panel,     -   fixation of the inside corner profile on the edge portion of the         gypsum plaster board panel,     -   insertion of a double-sided adhesive tape with a foam layer in         the recess,     -   adjustment and adaptation of the combination of gypsum plaster         board panel and inside corner profile in the inside corner         region,     -   exposing the outside of the double-sided tape, and     -   final arrangement and fixation/assembly of the gypsum plaster         board panel in the inside corner region.

EXPLANATION OF THE FIGURES

FIGS. 1 to 6 are intended to illustrate possible preferred embodiments and variants of the invention and their advantages without restricting the invention in any form.

FIG. 1 shows the inside corner profile 10 in cross section. The web 40 connects the long leg 20 to the short leg 30 and thus forms a receptacle, U-shaped in cross section, for the edge portion of a gypsum plaster board panel. The web 40 is extended beyond the attachment point 31 of the short leg 30. The web extension 41 has a shadow gap 43 on the back side of its end portion 42. The shadow gap 43 is designed in the form of a bevel and has a correspondingly flat (planar) shape.

FIG. 2 a shows the inside corner profile 10, which rests with the long leg 20 and the short leg 30 and the front side of the web 40 on the edge portion of a gypsum plaster board panel. The web 40 connects the long leg 20 to the short leg 30 and thus forms a receptacle, U-shaped in cross section, for the edge portion of a gypsum plaster board panel. The web 40 is extended beyond the attachment point 31 of the short leg 30. The web extension 41 has a shadow gap 43 on the back side of its end portion 42.

The paint application of the interior decoration (emulsion paint) terminates in the region of the shadow gap 43, so that the contact region between the plastic of the inside corner profile 10 and the emulsion paint is visually covered by the web extension 41. The aforementioned contact region relates to the possible color break line (color break edge).

The back of the web 40 and the back of the web extension 41 rest against a second gypsum plaster board panel. The double arrows in the cross section of the two gypsum plaster board panels illustrate the possible direction of movement of the panels. A movement of the panels can occur, for example, when exposed to thermal expansion or when the wall structure is subjected to mechanical stress.

The web extension 41 has a shadow gap 43 on the back side of its end portion 42. The shadow gap 43 is embodied in FIG. 2 a as a rounded bevel, i.e., in the embodiment shown, the outer side of the bevel is not planar, but rather curved inward.

The break edge of an emulsion paint applied to the inside of the room is visually covered by the shadow gap 43, so that any crack formation is less clearly detectable or not detectable at all for the viewer standing in the interior.

The web 40 has a groove-like recess 60 on the outside. The recess 60 is used to receive an adhesive (not shown) which allows the (possibly stretchable) fixing of the outside of the inside corner profile 10 to the second gypsum plaster board panel.

FIG. 2 b shows the inside corner profile 10 from FIG. 2 a in cross section. The cross section clearly shows that the shadow gap 43 on the back of the web extension 41 in the example shown is designed in the form of a curved bevel, i.e. the outside of the bevel has a correspondingly curved course.

The cross section also clearly shows that a further bevel 44 can also be arranged on the inside end portion of the short leg 30. This second shadow gap, designed as a bevel 44, does not have a rounded, but rather a planar outer side.

The additional bevel 44 has the same effect with regard to the perceptibility of a color break as the first shadow gap 43 against the end portion of the leg extension 41.

FIG. 3 shows a further variant of the inside corner profile 10. The inside corner profile 10 shown has an essentially triangular cross section in the front corner region 50 formed by the front side of the short leg 30 and the front side of the web extension 41.

FIG. 4 a shows an inside corner profile 10 in an alternative embodiment. The inside corner profile 10 is characterized in that the shadow gap 43 on the back side of the end portion 42 of the web extension 41 has a rabbet 45 in combination with two bevels 44.

The rabbet 45 covers the break edge of the emulsion paint over a larger region, so that a possible crack formation is even less noticeable for the viewer standing in the interior.

FIG. 4 b shows the inside corner profile 10 from FIG. 4 a in cross section, the stepped course of the shadow gap 43 becoming clearer. The stepped cross section results from the combination of a first bevel 44, a central rabbet 45 and a second bevel 44.

This alternative embodiment is considered to be particularly advantageous if the inside corner profile 10 is repeatedly painted over with emulsion paint as part of a repetitive room renovation (maintenance). The application of paint increases with each coat. The step- shaped cross section of the shadow gap provides at least two predefined color break lines with the two mutually offset bevels.

FIG. 5 shows an inside corner profile 10, which in the front corner region 50 formed by the front side of the short leg 30 and the top side of the web extension 41 has an inwardly curved profile (groove) in cross section.

In the example shown, the web 40 has a notch 61 instead of a groove-like recess for receiving adhesive. The notch 61 runs in the longitudinal direction of the profile and facilitates the expansion of the profile 10 when said profile is arranged on the edge-side portion of a gypsum plaster board panel. The expansion of the profile is deliberately made more difficult in that the length of the web 40 is dimensioned in such a way that the length of the web 40 on the inside directly or just corresponds to the thickness of the flat structural elements used. As a result, the inside corner profile rests against the edge region of a gypsum plaster board panel with a slight clamping tension.

FIG. 6 shows an inside corner profile 10, which is characterized in that the end portion of the short leg 30 tapers to a point and does not have a second shadow gap. This embodiment is preferred if the gypsum plaster board panel and the U-shaped receptacle, which is formed by the web 40, which connects the long leg 20 and the short leg 30 to one another, are connected to the inside corner profile 10 by means of adhesive or by mechanical fastening means.

In the embodiment shown in FIG. 6 the inside corner profile has a plurality of needle-like, pointed elevations on the inner side of the long leg. After insertion of a gypsum plaster board the needle-like, pointed elevations will penetrate the surface of the gypsum plaster board panel for an even better fastening of the profile to the edge portion of the panel.

In this case, the probability of a later expansion movement of the gypsum plaster board panel in relation to the inside corner profile is lower, so that a color break on the tapering end portion of the short leg 30 is less likely. For this reason, an additional shadow gap on the back end portion of the short leg 30 is not required.

Furthermore, the inside corner profile shown in FIG. 6 is characterized in that the web 40 has the same thickness throughout.

LIST OF REFERENCE SIGNS

-   -   10 Inside corner profile     -   20 Long leg     -   30 Short leg     -   31 Starting point of the short leg     -   40 Web     -   41 Web extension     -   42 End portion of the web extension     -   43 Shadow gap     -   44 Bevel     -   45 Rabbet     -   50 Corner region     -   60 Recess (groove)     -   61 Notch     -   62 Needle or pointed elevation with a barbed hook 

1. An inside corner profile for providing a low-maintenance expansion joint in a space at least partially designed with flat structural elements, the cross section of the inside corner profile having: a long leg on the back; and a short leg on the front; as well as a web that connects the short leg and the long leg; the web is extended beyond the attachment point of the short leg; and the web extension has a shadow gap on the back side of its end portion.
 2. The inside corner profile according to claim 1, wherein the web extension has at least one bevel on the back side of its end portion to form the shadow gap.
 3. The inside corner profile according to claim 1, wherein the web extension has at least one rabbet on the back of its end portion to form the shadow gap.
 4. The inside corner profile according to claim 1, wherein the web extension on the back of its end portion to form the shadow gap has: at least one bevel; and at least one rabbet.
 5. The inside corner profile according to claim 1, wherein the front corner region formed by the front side of the short leg and the top side of the web extension has a triangular cross section.
 6. The inside corner profile according to claim 1, wherein the front corner region formed by the front side of the short leg and the top side of the web extension has a concave shape on the outside in cross section.
 7. The inside corner profile according to claim 1, wherein the front corner region formed by the front side of the short leg and the top side of the web extension has a convex shape on the outside in cross section.
 8. The inside corner profile according to claim 1, wherein the short leg has a second shadow gap, on the back side of its end portion which is designed as a bevel and/or as a rabbet.
 9. The inside corner profile according to claim 1, wherein the surface of the shadow gap has a coating which reduces the adhesion of a paint to the inside corner profile.
 10. The inside corner profile according to claim 1, wherein the web has a recess and/or a notch running along the longitudinal axis of the profile on the outside on the portion located between the long leg and the short leg.
 11. The inside corner profile according to claim 1, wherein the length of the web is such that the inside length of the web corresponds to the thickness of the flat structural elements used or is slightly less than the thickness of the flat structural elements used, so that the inside corner profile rests against the edge region of a flat structural element with a slight clamping tension after it has been snapped on.
 12. The inside corner profile according to claim 1, wherein an adhesive strip having a protective strip or an adhesive tape with a foam intermediate layer is prefixed in the recess.
 13. The inside corner profile according to claim 1, wherein the long web has a plurality of needle-like elevations and/or a plurality of pointed elevations having a barbed hook spaced apart from one another on the inside.
 14. The inside corner profile according to claim 1, wherein the inside corner profile is made of a plastic or aluminum.
 15. A use of an inside corner profile according to claim 1 for construction of a drywall construction wall. 